KR820001255B1 - Arc-welding machine having prevent an electric shock - Google Patents

Abstract

The electric shock prevention device for use with an arc welder includes a High Frequency generation part comprising a HF oscillator(4), a HF amplifier(6) and HF transformer(5). The HF generation part is coupled to the secondary winding(L2) of the transformer(2), and the primary winding(L1) of the transformer is connected to the contact of the relay(3) and to the main power source(1) in series. The contaminated surface of the base metal(12) is broken by the HF heat, because the large capacitance having high loss-factor exsits between the electrode(13) and the base metal(12) when the electrode is contacted to the surface of the base metal(12).

Description

Lightning prevention device of arc welding machine

The accompanying drawings are electrical circuit diagrams of embodiments for explaining the invention.

The present invention relates to an electric shock prevention device of an arc welder, wherein the welding rod and the oxidized coating or paint layer on the surface of the welded body are burned by using high frequency when welding the welded object on which the oxide layer or the fouling layer is formed on the surface. The present invention relates to a device for energizing and welding primary primary electricity while the weldment is energized.

The electric shock prevention device of the conventional welding machine is manufactured mainly for the prevention of electric shock accidents of the welder, but the electric shock prevention function is sufficiently shown, but if the oxide film is formed on the surface of the welded object or if it is damaged by the paint, arcing does not occur and the welding is not performed. The delay caused efficiency deterioration. In addition, the high-sensitivity type electric shock prevention device may have malfunctioned due to extraneous high frequency pulse current when the welding cable is lengthened, thus losing the function of electric shock prevention.

That is, when arc welding is performed by high frequency current, the electrode and the welded material melted by the pulsation of the high frequency pulse current cause high frequency vibration, releasing harmful nitrogen or hydrogen, which are impurities contained in the melt, and bad after welding. It acts to lift the impurities such as silicon oxide and volatilize it from the melt, thus suppressing the occurrence of "brore hole" phenomenon.

In addition, the melt is known to have the effect of increasing the bonding strength between metal particles when solidifying crystals by high frequency vibration, thereby increasing the welding strength by miniaturizing the crystal grains of the welded portion.

However, in order to proceed smoothly, the higher the current waveform of the high frequency pulse is, the better. There is a drawback that quality improvement of welded parts cannot be expected.

In order to solve this drawback, Japanese Utility Model Publication No. 52-21316 is known to keep the distance between Tochikawa holding the welding device and the welding rod within 5 meters.

In addition, in order to prevent an electric shock such as an electric shock accident, a method of preventing electric shock has been adopted by inserting a current transformer into an output circuit of a welding transformer to detect and operate an output current.

In other words, it is also known to open a circuit by controlling a magnetic contactor inserted into a power supply circuit of the welding machine by operating the relay by using the increase in the secondary voltage of the welding machine as the arc disappears. However, in the above case, if the contact is poor due to the disconnection or the full-speed terminal of the coil or the connection wire of the relay, the secondary voltage rises, causing a dangerous condition.

In Japanese Patent Publications Nos. 40-6968 and 53-33534, in order to solve this problem, an excitation coil of an electromagnetic contactor is connected to a welding transformer with the same polarity as a welding machine and a voltage having a difference from the secondary voltage of the transformer is used. It is configured to apply to.

The purpose of the present invention is to not use the initial detection auxiliary power at the frequency of the normal exchange (60Hz) so that the arcing occurs even when the welding is not carried out within the range that the human body is not electrocuted even when the welding operation is not carried out and arcing occurs even during the initial welding. Instead, when the initial sensing auxiliary power is energized using the high frequency as the primary sensing electric power, the primary main electric is energized to provide an electric shock prevention device for the welder to generate arc.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the figure, 1 is a main power source, and the primary coil L ₁ of the welding machine 2 and the contacts of the relay 3 are connected in series. A high frequency generator consisting of a high frequency oscillator 4, a high frequency amplifier 6, and a high frequency induction transformer 5 is connected to the secondary coil L ₂ of the welding machine 2, and a tuning transformer is connected to the secondary coil of the transformer 5. A high frequency oscillator by connecting a sensing circuit device consisting of a primary winding 8-1 of 8 ', a secondary winding 8-2, and a capacitor C ₁ having high impedance and high impedance at a commercial frequency. When the sine wave oscillated in (4) passes through the high frequency generator and the sensing circuit device, it should have high input impedance at the frequency of commercial electricity.

Therefore, such a high frequency component has a high inductance component in the secondary coil L ₂ of the welder 2, so that only a slight loss of the high frequency occurs.

Thus, by such the power loss, and the deungjo signal generated at the secondary winding 8-2 of the high frequency tuned transformers (8 '), a part of the tuning signal is detected from the fluctuation amplification unit diode (D ₁₎ from the capacitor (C ₃₎ Since the DC current and the DC current flow through the resistor, the DC voltage is not affected by the lightning noise and the high frequency signal by tuning only the oscillation component in the high frequency detector R ₁ .

At this time, when the electrode 13 is in contact with the oxide or impurities on the surface of the object 12, a capacitive component having a large loss ratio is generated between the electrode 13 and the object 12. Since such an oxide film or an impurity layer is energized through a capacitive component, the oxide film is thermally destroyed by heat of high frequency.

In this case, a high frequency current flows a lot, so that the potential of the capacitor C ₃ is increased to generate a high low voltage moment.

Therefore, the instantaneous high voltage is applied to the input terminal (-) of the variable amplifier op amp 7 and the op amp having high input impedance until the capacitor C ₄ is charged through the resistor R ₂ . The voltage difference occurs between the input terminals (+) and (-) of the op amp 7. This voltage difference is amplified by the amplification factor set by the resistor (R ₃ ) and the resistor (R ₄₎ to obtain the output of the variance amplifier, and the comparator (8) is set to the resistor (R ₅ ) and the resistor (R ₆ ). When the set voltage is lowered, the output of the comparator 8 changes from L to H. At this time, the trigger NAND gate 11 is triggered, and the output of the NAND gate 11 becomes L, and is composed of gates 9 and 10. In the memory circuit, the gate 10 is switched to H, and the NAND gate 11 is switched to L. FIG. Accordingly, the output of the NAND gate 10 applies a voltage to the base of the transistor Q ₁ through the resistor R ₁₅ to conduct the emitter-collector, which energizes the relay ON, thereby turning on the relay contact to turn on the welding machine ( The main power source 1 is applied to the primary coil L ₁ of 2).

Therefore, the high frequency current induced in the secondary coil L ₂ of the welding machine 2 breaks the oxide film of the welding rod 13 and the welded object 12 and conducts high frequency heating while conducting high frequency heating, thereby generating a smooth main power arc. The op amp 7 is completely charged to the capacitor C ₄ via the resistor R ₂ , so that there is no voltage difference between the input terminals (+) (−) of the op amp 7. As the output becomes L, the output of the NAND gate 11 is returned to H, and the output of the NAND gate 10 is arc welded to the main power supply as configured to stop oscillation of the high frequency oscillator.

After welding through the above process, a high no-load voltage is generated in the secondary coil (L ₂ ) of the welding machine (2) and this no-load voltage is divided voltage divided between the resistor (R ₇ ) and the resistor (R ₈ ) When the welding is over and the high voltage is set after welding, the voltage at both ends of the resistor (R ₈ ) is half-wave rectified by the diode (D ₂ ) and the direct current from the capacitor (C ₆ ) becomes the zener diode. When the zener voltage of (ZD) is exceeded, this current is divided again in the resistors R ₁₀ and R ₁₁ , and a voltage is applied to the base of the transistor Q ₂ to turn on the emitter collector of Q ₂ . Therefore, as the collector voltage of the transistor Q ₂ becomes L, the potential across the capacitor C ₇ is discharged through the resistor R ₁₃ .

The voltage discharge is discharged only in the reverse direction due to the diode D ₃ , and the time constant until the discharged voltage reaches the voltage at which the NAND gate 9 is operated may be determined as the delay time of the electric shock prevention.

When the delay time set in this manner has elapsed, the NAND gate 9 is operated to return the memory circuit. Therefore, the output of the NAND gate 10 becomes L to turn off the transistor Q ₁ and open the contact of the relay 3 to cut off the main power supply 1 from the primary coil L ₁ of the welder 2. At the same time, when the high frequency oscillation occurs and the high frequency output fluctuates, and the output of the comparator 8 becomes H again, the output of the NAND gate 9 becomes H, so that the resistance R ₁₄ connected in parallel with the diode D ₃ in the reverse direction is obtained. Since the capacitor C ₅ is to be charged, it delays the time that the NAND structure of the NAND gate 11 can be NAND, so that the NAND gate 11 becomes an NAND structure only after the op amp 7 is stabilized, and thus the welder 2 The power is cut off from the primary coil (L ₁ ) of.

In the figure, C ₂ is a capacitor, and R ₉ , R ₁₀ , R ₁₁ , and R ₁₂ are resistors.

As described above, according to the present invention, it is possible to stably weld regardless of the malfunction or cable length as in the prior art, and to prevent electric shock during operation, and occurs when the electric shock protector is attached even when the surface of the welded object is damaged. It is possible to improve the work efficiency by eliminating the closed stage where the initial arc is less likely to occur.

Claims (1)

As described above in the text, in an electric shock prevention device for an arc welder, a high frequency induction transformer comprising a high frequency oscillation (4), a high frequency amplifier (6), and a high frequency induction transformer (5) is connected to a power supply control circuit of a welding machine. The secondary coil of (5) is connected to the detector consisting of the detector 8 'and the condenser C ₁ and the secondary coil of the welding machine, and then the sensing amplifier connected to the secondary coil 8-2 of the detector. Lightning prevention device of arc welding machine.

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